Strict Blood Sugar Lowering Wont Ease Diabetes Heart Risk
WEDNESDAY Dec. 17, 2008 -- Intensive lowering of blood sugar in people with poorly controlled type 2 diabetes does not have a significant effect on reducing cardiovascular events, such as heart attack and stroke, a new study finds.
"You can decrease cardiovascular events in patients with type 2 diabetes by good treatment of lipids [cholesterol], blood pressure and other cardiovascular risk factors," noted lead researcher Dr. William Duckworth, from the Phoenix Veterans Affairs Health Care Center in Arizona. "But among older patients whose risk factors are controlled, intensive glucose control does not add any significant benefit," he said.
That runs counter to the conventional wisdom on the issue, which holds that intensive lowering of blood sugar should reduce cardiovascular events.
"But it's never been proven," Duckworth said. And given the findings of the new study, "time and money may be better expended by doing more work on lipids, blood pressure, diet and exercise," he added.
The report was published in the Dec. 17 online edition of the New England Journal of Medicine.
For the study, called the Veterans Affairs Diabetes Trial (VADT), Duckworth's team randomly assigned almost 1,800 patients averaging 60 years of age to intensive blood sugar control or to standard blood sugar control. All of the patients had experienced suboptimal responses to treatment for type 2 diabetes.
During 5.6 years of follow-up, 264 of the patients receiving standard blood sugar control experienced a heart attack or stroke, died from heart disease, developed heart failure, had surgery for heart disease or had an amputation made necessary by poor circulation.
But so did 235 of the patients who received intensive blood sugar control.
Moreover, there was no difference between the groups in deaths from any cause or other complications from diabetes such as kidney and vision problems, the researchers found.
The value of intensive blood sugar control has become a highly debated topic, especially since two recent studies looking at the benefits of aggressively lowering blood sugar in people with type 2 diabetes came to different conclusions.
One study, the ADVANCE (Action in Diabetes and Vascular Disease) trial found a 21 percent reduced risk for kidney disease in patients on tight glucose control. On the other hand, the ACCORD (Action to Control Cardiovascular Risk in Diabetes) trial found a 22 percent increased risk of death for those on the stricter regimen.
Dr. David Nathan, a professor of medicine at Harvard Medical School and chief of the Diabetes Unit Medical Service at Massachusetts General Hospital in Boston, doesn't believe the new study adds much to the mix. And while dramatically lowering blood sugar may not have a benefit for cardiovascular disease, it does have a benefit in slowing or preventing other complications of diabetes, Nathan said.
"Neither study demonstrated a benefit for cardiovascular disease, and ACCORD was stopped early because of increased mortality in the intensive group," Nathan said. "The increased mortality in ACCORD suggests caution in aiming for very low blood sugar levels, which has been the American Diabetes Association's -- and my -- recommendation for years," he said.
"The bottom line here is that diabetes treatment aimed at blood sugar of less than 7 percent on blood sugar tests is of benefit for eye, kidney, and nerve disease, which was established by other studies, but probably underpowered in the VADT, but [it] may not benefit heart disease outcomes," Nathan said. "The VA study doesn't add much to the previously published studies, and it shouldn't be used to loosen the current recommendations," he said.
For more about diabetes, visit the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.
Posted: December 2008